Multiple choice

The rails of a railway track separated by 1 m are connected to a millivoltmeter. The rails are insulated from each other and the ground. A superfast train travels at a speed of 135 km/h. What will the reading of the millivoltmeter if the horizontal component of the Earth's magnetic field at that place is 0.2 Gauss?

  1. 5.33 mv

  2. 0.75 mv

  3. 1875 mv

  4. 6750 mv

  5. 2.7 mv
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The reading of the millivoltmeter = motional emf produced across the axle = BvlSpeed v = 135 km/h = 135 x 5/18 m/s = 37.5 m/sMagnetic field B = 0.2 G = 0.2 x 10- 4 T Length l = 1 m Therefore, the reading of the millivoltmeter = 0.2 x 10- 4 x 37.5 x 1 = 0.00075 V = 0.75 mV

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